Touch-sensitive displays are well known in the art. For example, touch screens are used in many electronic devices to display graphics and text, and to provide a user interface through which a user may interact with the electronic devices. A touch screen detects and responds to contact(s) on the touch screen. A device may display one or more soft keys, menus, and other user-interface objects on the touch screen. A user may interact with the device by contacting the touch screen at locations corresponding to the user-interface objects with which he/she wishes to interact.
One problem associated with using touch screens on electronic devices is the unintentional activation or deactivation of functions due to unintentional contact with the touch screen. Thus, when a predefined lock condition is met, the electronic device may be locked automatically to avoid receiving unintentional activation or deactivation of functions due to user's unintentional contact. Alternatively, the electronic device may be manually locked by the user anytime. Electronic devices with touch screens may be unlocked by any of several well-known unlocking procedures, such as entering pre-defined passwords, pressing pre-defined buttons, entering pre-defined gestures, touching pre-defined locations on the touch screen, etc. However, these conventional unlock procedures are either complicated or not user-friendly. Thus, there is a need for a more efficient, user-friendly procedure for unlocking an electronic device.